Bonding aluminum or aluminum base alloy to ferrous metal by means of an alloy bond



April 14, 1953 w. H. Pl-:RsHlNG l-:TAL BONDING ALUMINUM OR ALUMIN FERRou Mak/wa UM BASE ALLQY To F AN ALLOY BOND 1947 4 S METAL BY MEANS O Filed June 19,

Patented Apr. 14,1953

BGNIDHNGl ALUMINUM OR ALUMINUM BASE ALLOY TO FERROUS METAL BY MEAN S OF AN ALLOYv BONDv William ILL-Pershing, Bedford, J uliusJ McClain, Anderson, and John A. Fulwider, Bedford, Ind., assignorsA to General Motors Corporation,l Detroit, Mich., a corporation of Delaware Application June-19, 1947,. Serial No. 755,662'

This invention relates to the bonding ofV aluminum or an aluminum base alloy to steelor other ferrous metal by means of an alloy bond.

The primary object of the invention is to provide a simple and'practical procedure. for strongly bonding aluminum or aluminum base alloys to a steel or other ferrous metal surface by an alloy bond.

In carrying out the process of the present invention the steel orV other ferrous metal part. or member is subjected to an acid etch to prepare thev surface for the reception of a coating of a suitable bonding alloy. If the parts have foreign matter thereon, such as oil for example, they are cleaned as by sand blasting or .by washing in a suitable cleaner before being given the acid etch. After being acid etched the parts are thoroughly washed. -After being washed the etched parts are kept free of moisture and oxide formation until they are to be placed in a molten bath` of the bonding alloy. If the bonding alloy casting is to be applied immediately after the washing operation the parts are simply dried and then placed in the bonding alloy bath. Where there is any considerable time interval between the etching and washing treatments, and the application of the bonding coating the parts may be kept free of oxide formation by immersing the parts inV a suitable flux bath. When ready to process the parts in the bonding bath the parts are removed from the flux bath, thoroughly dried and then immersed in a bath of the molten bonding alloy for a short time to heat the ferdrawn from the bath and have a fused coating of the bonding alloy thereon. The part with the fused coating is then placed in proper position in a die or mold with as little delay as possible and molten aluminum or aluminum base alloy cast. therearound. The parts are then cooled or allowed to cool. The result is a composite article comprising aluminum or aluminum alloy strongly bonded to ferrous metal by an alloy bond.

The acid etch or pickling treatment preferably consists in immersing the ferrous metal part in concentrated hydrochloric acid (22 Beaum) for example, for a short time. With acid of this concentration an etch at a temperature of 90 to 100 F. for approximately live to ten minutes has proven highly satisfactory. The etched parts are then thoroughly washed. In one application of the process the parts are thoroughly washed in hot water for a minimum time of two minutes. In ordinary practice the washed parts 'z claims. (ci. ca -204) are then held in a flux bath, such as, for example, a 10% solution of zinc ammonium chloride, until ready to be processed in the bonding alloy bath. The iiux bath is kept hot; for example, a temperature of l50` F. is maintained. When ready to process in the molten bonding bath the parts are removed from the hot flux bath and thoroughly dried as by means of an air stream. The `bonding alloy bath is a zinc base alloy containing tin and a minor amount of aluminum. A bonding alloy that has proven particularly advantageous is one composed substantially as follows: 10% tin, 0.4% aluminum and the balance Zinc. The zinc base alloy bath containing tin and aluminum is maintained at a temperature of about l300 F. to abo-ut 1420 F. The ferrous metal part is immersed in the heated bonding alloy bath and allowed to remain therein for a time at least suicient to'raise the temperature of theferrous metal to above the fusion temperature of the alloy of the bonding bath. The ferrous metal part is then removed from the bonding alloy bath and has thereon a fused coating of the bonding alloy. Excesscoating metal is removed as by shaking the coated part and/ or by scraping. The coated part is'promptly placed in a mold or die and, before the part cools below the point where the coating is mushy or molten, molten aluminum or aluminum base alloy is lcast therearound. Any mold or die composition may be employed, for example, metal, sand (either green or dry), plaster, etc. or combinationsl of these materials. Y

Reference is herewith made to the accompanying drawings which illustrate application of the invention to the formation of composite gear blanks consisting of a steel hub and aluminum or aluminum alloy strongly bonded thereto 'by an alloy bond. In the drawings:

Figures 1 to 4 inclusive are views illustrating somewhat diagrammatically, etching, washing, fluxing and coating, respectively, of a steel hub.

Figure 5 is a sectional view showing acoated hub located in position in a mold or die prior to casting aluminum or an aluminum .base alloy therearound, the coating beingshown of greater relative thickness than the hub for purposes of claritl7 of illustration.

In Figure 1 is shown a steel hub I0 immersed in a concentrated solution of hydrochloric acid l2 in tank I3. Tongs I4 are shown supporting the hub in the acid. Figure 2 illustrates the step of Washing the etched hub, the hub being shown immersedin hot water I6 in tank I8. Figure 3 'shows the etched and washed hub being held in a hot ux solution 20 in container 2| to protect the hub from oxidization. This step may be omitted if the etched and Washed hub is to be immediately dried and immersed in the molten bonding alloy bath.V Where the flux bath treatment is used the parts are, of course, also thoroughly dried before immersion in the molten bonding alloy. Figure 4 shows the steel hub being heated in a molten bonding alloy bath 22 in pot 24. In this application the steel hub is a 2" hexagonal hub having a his" diameter center hole. The hub is held for two minutes in the bonding bath composed of tin, 0.4% aluminum and the balance zinc maintained at a temperature of about 1390 to 1400 F. The heated hub is then removed, excess zinc alloy shaken therefrom or otherwise removed and the heated hub having the fused coating thereon placed .in a die or mold. Figure 5 shows the hub having thereon the bonding coating 26. In this figure, 28 represents a metal mold or die part having means 32 for centrally locating the coated hub. The metal die member is preferably preheated to. a temperature on the order of 100-500 F. Once the hub is located in position an upper baked sand mold part 34 is placed on the lower metal mold or die part and aluminum or aluminum alloy is poured into the mold as soon as possible. The dry sand mold part 34 has a cavity 36 at the Vupper end thereof forming a receptacle to receive the molten aluminum or aluminum alloy in the casting operation. A plurality of equally spaced passages 38 lead from cavity 36 to the mold cavity 40 formed between the die 28 and sand mold section 34. A molten aluminum alloy heated to a temperature -of 13801420 F. is then poured into the receptacle 36 from where it flows through the passages 38 into the mold cavity. Sufcient aluminum is poured to completely ll the mold and passages and to leave an excess in the receptacle 36 to take care of shrinkage as the aluminum solidies in the mold. After solidication the composite article is removed from the mold. The process results in a composite gear blank comprising a steel hub to which is strongly bonded the cast aluminum by means of an alloy lbond.

In making the gear blanks best results have been obtained when a steel such as C1117 is employed for the hub. This type of steel has a manganese content on the order of 1 to 1.30% and a sulphur content of .08 to .13%. One example of an aluminum base alloy that has been employed in producing the composite gear blanks 'consists of 3.5 to 4.5% copper, 1,'7 to 2.3% nickel, v1.2 to 1.8% magnesium and the balance aluminum plus minor amounts of impurities found in aluminum alloys.

We claim:

1. A method of forming. a composite metal article which comprises acid etching a ferrous metal member, immersing said etched ferrous metal member in a molten zinc base alloy bath containing small amounts of each of tin and aluminum, said bath being `at a temperature on the order of 13001420 F., holding said etched ferrous metal member in said molten bath until the ferrous metal member is heated to said bath temperature, then removing the ferrous metal member from the bath, said ferrousmetal member having thereon when removed from the bath a molten coating of said zinc base alloy, placing said coated ferrous metal member in a mold, and, *before the coating has completely solidified, casting a molten metal of the class consisting of 4 aluminum and aluminum base alloys around the coated ferrous metal member.

2. A method of forming a composite metal article which comprises immersing a steel member in a concentrated hydrochloric acid bath maintained at a temperature of yabout to 100 F. for about five to ten minutes, removing the etched steel member, thoroughly Washing and then dry- Ying the same, then immersing the treated steel member in a molten alloy bath composed approximately as follows: v10% tin, 0.4% aluminum, balance zinc, said bath being maintained at a temperature of about l3001420 F., heating the steel member in said alloy bath until it is at substantially bath temperature, then removing said steel member from the bath, said steel member having thereon when removed from the bath a molten coating of said alloy, placing said coated steel member in a mold, and, before the coating has completely solidified, casting in said mold and around the coated steel member a molten aluminum base alloy heated to a temperature of about 1380" F. to 1420o F.

3. A method of forming a composite gear blank which comprises immersing a steel hub containing about 1 to 1.30% manganese and'.08 to .13% sulfur in a concentrated hydrochloric etching bath maintained at a temperature of about 90 to F. for about 5 to ten minutes, removing the etched steel hub, thoroughly washing the hub, immersing the washed hub in a heated flux bath, drying said fluxed hub, then immersing the hub in a molten alloy bath composed approximately as follows: 10% tin, 0.4% aluminum, balance zinc, said zinc alloy bath being maintained at a temperature of about 1390 F. to 1400 F., heating the hub in said molten zinc alloy bath until it is at approximately said bath temperature, then removing the heated steel hub from the molten zinc alloy bath, said steel hub having thereon when removed from the bath a molten coating of said Zinc alloy, placing said coated steel hub in a mold, and, before the coating has completely solidified, casting in said mold and around the coated steel hub a molten aluminum base alloy heated to a temperature of about 1380 F. to 1420o F.

4. A method of forming a composite metal article which comprises etching a ferrous metal member, immersing said etched ferrous metal member in a molten zinc base alloy bath containing small amounts of each of tin and aluminum, said zinc base alloy bath being maintained at an approximate temperature of 1300 F. to 14.20 F., and said etched ferrous metal member being substantially at bath temperature while in said molten zinc base alloy bath, then removing said ferrous metal from said molten zinc base alloy bath, said ferrous metal member having thereon when removed from the bath a molten .coating of said zinc base alloy, placing the coated ferrous metal member in a mold, and, before the 'coating has completely solidied, casting a molten metal of the class consisting of aluminum and aluminum base alloys around said coated ferrous metal member.

5. A method of forming a composite metal .article which comprises acid etching a ferrous metal member, immersing said etched ferrous metal member in a molten zinc base alloy bath containing small amounts of each of tin and aluminum, said zinc base alloy bath being maintained at an approximate temperature of 1300 to 1420 F., holding said etched ferrous metal member in said molten` zinc base alloy bath until the ferrous metal member is at substantially bath temperature, then removing said ferrous metal member from said molten zinc base alloy bath, said ferrous metal member having thereon when removed from the bath a molten coating of said zine base alloy, placingr the coated ferrous metal member in a mold, and, before the coating has completely solidied. casting a molten aluminum base alloy around said coated ferrous metal member.

6. A method as in claim 5, in which the zinc base alloy consists essentially of approximately 10% tin, .4% aluminum and the balance zinc.

7. A method as in claim 5, in which the temperature of said Zinc base alloy bath is Within the approximate range of 1390 to 1400 F. and the molten aluminum base alloy is at a tempera- 6 ture Within the approximate range of 1380 to 1420" F.

WILLIAM H. PERSHING. JULIUS J. MCCLAIN. JOHN A. FULWIDER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,755,559 Pietsch Apr. 22, 1930 1,807,689 Deputy June 2, 1931 1,830,652 Glenner Nov. 3, 1931 2,123,181 Deputy July 12, 1938 2,197,622 Sendzimir Apr. 16, 1940 2,265,243 McCullough et al. Dec. 9, 1941 2,326,418 Van Amerongen et al. Aug. 10, 1943 

1. A METHOD OF FORMING A COMPOSITE MATAL ARTICLE WHICH COMPRISES ACID ETCHING A FERROUS METAL MEMBER, IMMERSING SAID ETCHED FERROUS METAL MEMBER IN A MOLTEN ZINC BASE ALLOY BATH CONTAINING SMALL AMOUNTS OF EACH OF TIN AND ALUMINUM, SAID BATH BEING AT A TEMPERATURE ON THE ORDER OF 1300*-1420* F., HOLDING SAID ETCHED FERROUS METAL MEMBER IN SAID MOLTEN BATH UNTIL THE FERROUS METAL MEMBER IS HEATED TO SAID BATH TEMPERATURE, THEN REMOVING THE FERROUS METAL MEMBER FROM THE BATH, SAID FERROUS METAL MEMBER HAVING THEREON WHEN REMOVED FROM THE BATH 